The year was 1964, the Dallas Cowboys had been in the league for only fours years, They had not had a winning year yet. The owner of the Cowboys had hired a defensive coach to be the first head coach in Cowboys history. After yet another losing year in 1963 Clint Murchison made a decision that to this day can be traced back to the defining moment in Dallas Cowboys history. He gave the head coach of the team a ten year contract extension. In the next ten years the Cowboys went on to win a Super Bowl and the NFC championship twice. He was named coach of the year three times in those ten years. This however is not the most notable of his achievements. Tom Landry, Cowboys head coach, invented the Flex Defense, a hybrid of the 4-3 defense he had also invented. This changed the game of football forever, not only cementing Ton Landry's legacy in Cowboys history but in the history of the NFL. He was the First football guru or genius or whatever todays hot new word would be for coaching greatness and still is one of the winningest coaches in professional football history. That is why 1964 was the day that changed history for the Dallas Cowboys and the National Football league. Everything todays great coaches know about defense starts and ends with the great Tom Landry.